Well done again, and wishing you continued success with your app!
Initially I would use Instagram and follow some hashtags and like people's posts and follow them to get them to look at my profile (I got about 150 downloads that way).
One day I decided I wanted to try out ReactJs and so I made a web calculator version [0]. The goal was to make something better than the current incumbent (Black Iron Beast). This turned out to be super helpful. It usually ranks number 2 on most Google queries for 5/3/1 calculators and lead to about 200 downloads for the app.
I also started using Apple App Store Search Ad with their $100 credit and honestly the result are great. Having your app show up first for some keywords is a huge boost.
I’m building Conjure[1] a habits, behavior and goals platform, so I track everything from ‘habits’/‘productivity’/‘quantified-self’ type keywords, to people looking for alternatives to XYZ product name, to specific questions I’ve answered before (eg organization, time tracking, building exercise habit, achievement, etc).